Cardiovascular disease (CVD) is the most frequent cause of morbidity and mortality in chronic renal failure (CRF) patients. Accelerated calcifying atherosclerosis, medial calcification, and valvular calcification are hallmarks of CVD in the dialysis population. The mechanisms by which uraemia promotes vascular calcification and the relationship between arterial wall calcification and atherosclerosis are poorly understood. We surgically induced CRF in apolipoprotein E knockout (apoE-/-) mice to study a possible acceleration of aortic atherosclerosis, the degree and type of vascular calcification as well as factors involved in the calcification process. Finally we investigated appropriate treatment measures. Atherosclerotic lesions in the thoracic aorta were significantly larger in uraemic apoE-/- mice than in non-uraemic controls. The relative proportion of the calcified area to the total surface area of both atherosclerotic lesions and lesion-free vascular tissue was increased in the aortic root of uraemic apoE-/- mice when compared with controls. The accelerated atherosclerosis was associated with an increase in aortic nitrotyrosine expression, indicating enhanced oxidative stress, and an increase in plaque collagen content, indicating changes in plaque composition. N-acetylcysteine (NAC) treatment slowed the rapid progression of atherosclerotic lesions and reversed the increase in plaque collagen content compared with placebo treatment.NAC-treatment also reduced nitrotyrosine expression in uremic apoE-/- mice whereas the degree of macrophage infiltration was unchanged. Sevelamer treatment delayed not only vascular calcification but also atherosclerotic lesion progression in uraemic apoE-/- mice. These treatment effects also were associated with diminished oxidative stress and were independent of cholesterol lowering. We anticipate that this experimental model will prove to be useful to test other treatment strategies aimed at decreasing the accelerated atherosclerosis and arterial calcification of the uraemic state.

Reactive oxygen species, formed in various biochemical reactions, are normally scavenged by antioxidants. Glutathione in its reduced form (GSH) is the most powerful intracellular antioxidant, and the ratio of reduced to oxidised glutathione (GSH:GSSG) serves as a representative marker of the antioxidative capacity of the cell. Several clinical conditions are associated with reduced GSH levels which as a consequence can result in a lowered cellular redox potential. GSH and the redox potential of the cell are components of the cell signaling system influencing the translocation of the transcription factor NF kappa B which regulates the synthesis of cytokines and adhesion molecules. Therefore, one possibility to protect cells from damage caused by reactive oxygen species is to restore the intracellular glutathione levels. Cellular GSH concentration can be influenced by exogenous administration of GSH (as intravenous infusion or as aerosol), of glutathione esters or of GSH precursors such as glutamine or cysteine (in form of N-acetyl-L-cysteine, alpha-lipoic acid). The modulation of GSH metabolism might present a useful adjuvant therapy in many pathologies such as intoxication, diabetes, uremia, sepsis, inflammatory lung processes, coronary disease, cancer and immunodeficiency states.

Twenty-six nitrogen balance studies were performed in 15 patients with severe uremia (Ccr mean value 5.1, range 2.3-8.5 ml/min) treated with an unselected protein-poor (16-20 g protein/day corresponding to 2.6-3.2 g N/day) diet and oral supply of the essential amino acids including histidine (2.6 g N/day). The general condition improved and the concentration of serum urea nitrogen decreased. The nitrogen balance, corrected for changes in total urea pool, was negative on the diet alone,-1.46 plus or minus 1.15 g N/day (mean plus or minus SD), but was positive when the essential amino acids were supplied, plus 0.84 plus or minus 0.68 g N/day. In four patients studied after 3 to 26 months of diet and amino acid therapy, during which time a further deterioriation of the renal function had occurred, the nitrogen balance was around zero in three and negative in one patient (-1.2 g N/day). The results show that it is possible with our new regimen to attain positive nitrogen balance or nitrogen equilibrium in severely uremic patients without excessive accumulation of urea in the body fluids.

Twenty-six uremic patients - serum urea nitrogen (SUN) 110 MG/100 ml plus or minus 22.8 (mean plus or minus SD), serum cretinine (S-Creat) 13.2 mg/100 ml plus or minus 2.27, ratio SUN/S-Creat 8.6 plus or minus 2.26, and endogenous creatinine clearance (Ccr) 3.86 plus or minus 1.41 ml/min - were treated for three months or longer with an unselected protein-poor (16-20 g protein/day) diet with oral supply of the essential amino acids including histidine in high doses as coated tablets. The amino acids were instituted after an initial diet only period (mean 0.4 months). The average treatment time was 8.4 months (range 2.7-33.6). An improvement of the general condition was obtained, persisting for several months. SUN and SUN/S-Creat decreased on the diet alone, continued to decrease after one month, and increased slightly again after three months of treatment, but did not reach the initial levels for several months in spite of an almost doubled nitrogen intake. S-Creat increased after six months indicating a further deterioration of the renal function. In patients with initially low serum total protein (smaller than 6.5 g/100 ml, 9 patients), albumin (smaller than 3.5 g/100 ml, 10 patients), and total iron-binding capacity (smaller than 260 mug/100 ml, 11 patients) the values increased after one month on amino acids and were thereafter stable. No signs of bleeding tendency, progressive muscle atrophy, or progressive peripheral neuropathy were observed. - Five patients died due to cardiovascular maladies. A further 13 patients were withdrawn for medical reasons (overhydration, 4 patients; hypertension, 1 patient; nausea and vomiting, 7 patients; and pericarditis, 1 patient). - The renal function improved in one patient. Four patients received home dialysis training, three a kidney transplant. - The results indicate that it is possible to keep severely uremic patients free from uremic symptoms, counteract protein depletion, and even improve the nutritional status during long-term treatment with an unselected protein-poor diet supplementd with essential amino acids.